A study on the synthesis and anion recognition of a chitosan-urea receptor

A new chitosan based colorimetric anion receptor bearing nitrophenyl as a chromogenic signal group, and urea moiety as recognition site was designed and synthesized. The receptor structure was characterized by FTIR and 1H NMR. The sensing abilities of the receptor for anions were investigated with UV-vis methods. During the addition of PO43− and F− anions, the sensor responded with a dramatic color change, and no change was observed in the presence of other anions. The UV-vis absorption titration data showed that the receptor shows selective recognition and sensing in DMSO-H2O (1%) for PO43− and F− anions. The Job's curve showed that 3 : 2 stoichiometry complexes were formed between the receptor and the anion.